Competition between young cedar (Cryptomeria japonica ) and broad-leaved trees at different slope positions in a non-weeded stand in Southern Kyushu

Abstract

The objective of this study was to examine the competition between Japanese cedar (Cryptomeria japonica) and broad-leaved trees at different slope positions in a 5-year-old non-weeded cedar stand in Kagoshima University Forest, Southern Kyushu. We investigated the height growth of planted cedar and broad-leaved trees without weeding treatment stand, and analyzed the species composition and size of broad-leaved trees at different slope positions to compare 5 m strips. We examined the degree of height growth inhibition to compare the affects non-weeding treatment with complete yearly weeding treatment in adjoining even-aged stands. On the upper slope, the height of cedars in the stand without weeding was four-fifths that of cedars in the stand with weeding but was higher than that of broad-leaved trees. In contrast, on the lower slope, broad-leaved trees suppressed cedar height growth in the stand without weeding to 35% of that in the stand with weeding. On the basis of these results, we suggest that weeding in cedar stands can be reduced on upper slopes but is necessary on lower slopes.